Firearm upper receiver



FIG. 1 is a top left perspective view of a firearm upper receiver;

FIG. 2 is a top right perspective view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a front view thereof;

FIG. 5 is a top view thereof;

FIG. 6 is a bottom view thereof;

FIG. 7 is a right view thereof;

FIG. 8 is a left view thereof; and,

FIG. 9 is a perspective view of a firearm comprising the firearm upper receiver.

The broken lines in the figures are for illustrating environment and unclaimed features and form no part of the claimed design. 

CLAIM The ornamental design of a firearm upper receiver, as shown and described. 